Earlier this month, my friend Rebecca Skloot replaced her hulking big-box TV - I can vouch for its girth, having moved it once - with a flat-screen no thicker than an iPad. She turned it on and, horror of horrors, the picture was lousy.

Displeased, she turned to Google for help. What the search engine delivered was a mess, a collection of spammy sites riddled with ads. So she turned to Twitter, posting: "Old TV died, got newfangled LED TV. Shocked how bad/fake movies look! . . . Others have this prob?"

Skloot's story seems ever more common these days. Google is facing withering criticism from tech bloggers and search engine experts who say the world's premier gateway to digital information is increasingly being gamed by spammers. Google, they say, is losing.

One tech blogger, the well-known iPhone app developer Marco Arment, wrote a post about "Google's decreasingly useful, spam-filled web search." Another blog offered a piece titled "On the increasing uselessness of Google." Yet another headline spoke of "Trouble in the House of Google."

Data seem to back them up. Google's success rate, as measured by the percentage of users visiting a Web site after executing a search, fell 13 percent last year, according to Experian Hitwise, which monitors Web traffic. Microsoft's Bing search engine increased its search efficiency by 9 percent over the same period.

Although there could be several reasons for the disparity, one is most certainly spam in Google's results, analysts said.

"It's clear that Google is losing some kind of war with the spammers," said tech guru Tim O'Reilly, who often cheers Google's technology. "I think Google has in some ways taken their eye off the ball, and I'd be worried about it if I were them."

Google recently responded with its own blog post, acknowledging some problems and promising to fix them.

"Reading through some of these recent articles, you might ask whether our search quality has gotten worse," the statement said. "The short answer is that according to the evaluation metrics that we've refined over more than a decade, Google's search quality is better than it has ever been in terms of relevance, freshness and comprehensiveness. . . . However, we have seen a slight uptick of spam in recent months, and while we've already made progress, we have new efforts underway to continue to improve our search quality."

Google's predicament, analysts say, comes at a critical moment in the life of the Internet. The company generates billions of dollars in revenue from search ads. But social networks such as Twitter and Facebook offer people the ability to gather information online the way we always have offline - by asking people we know. Studies show we often give greater trust to information gathered from sources we know than from those we don't.